According to Macciamo E3b (Or at least some of E3b) and J2b2 is part of indoeuropean expansion! IndoEuropeans were not strictly R, before the expansion they had absorbed other haplogroups as well. Lack of African haplo L in countries with E3b majority shows, that they were marring strictly white women, contrary to the perception that east Africa was the birthplace of E, and so small amounts of African L was expected.
So about your E3b could be result of indoeuropean expansion.