If lactose persistence arose in R1b we would find it in Spain, and the R1b V88 distribution in Africa doesn't match the lactose persistence distribution in Africa.
The best explanation is lactose persistence spreading with Germanic migrations and their milk drinking culture around 500 BC. Milk consumption is highest in Sweden. This seems really rather obvious.
There was a recent study about lactase persistence in Africa which is very informative:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3980415/
Lactase persistence in Africa derives from five separate mutations, only one of which is the European variant, or 13910T. The authors maintain that three of the others spread from the general area of the Levant/Arabia and one arose in East Africa. They have high frequency in pastoralist societies. So, there is nothing uniquely "European" about mutations for Lactase Persisence or selection for them in such societies.
In western Africa, the Hausa, a Chadic speaking equestrian based society of pastoralists, who consume a lot of milk products, including fresh milk, have levels of 20-40% R1b, but all of it is V88, for which a steppe origin and Indo-European connection has never, to my knowledge, been posited. It may be true that they were pastoralists even in the Levant or Anatolia, but would they necessarily be the only haplogroup in Anatolia that kept cattle? Anyway, the frequency of 13910T in them is either 13.90 or 22.92 percent. They also show a frequency of 11.55% of the 14010 derived allele for Lactase Persistence.
The Fulani, also pastoralists who incorporate milk products into their diet, but in their case Niger Congo speaking, have a frequency of 14.3% for R1b V-88, but a frequency of the European 13910T variant of from 11 to 39% depending on the area and the study. They also have from 12 to 14% frequency of the 14010 Lactase Persistence variant.
On the other hand, the Oudelme of Cameroon are 95% V88 but in the one test done for the presence of lactase persistence alleles, their score was 0. Now, that seems a little odd to me, so perhaps they have some, but anyone who wants to draw any conclusive correlation between the presence specifically of R1b V88 and the "European" variant of a Lactase Persistence mutation is going to have to do more research.
Oh, and the drawing of a correlation is made more difficult by the data on North Africans. The "European" Lactase Persistence variant has frequencies in Mozabite Berbers of 22,7% and in general Algerians of 33.3%, depending on the study. Their level of R1b is, from a quick search, only about 3%, all of it V-88. There's no data for other areas.