I presume it must have been that, yes. It does look like an attempt to lose a pawn Although 7 .. cxb5 8 Bxa8 d5 seems to trap whites bishop. 

If white goes 5 cxb5 ab 6 Nd4 then black can avoid a gambit with c6 (into above), or Ra5. But 6 .. d5 ^ 7 Nxb5 h5, c6, e5 etc is nice compensation too.

There is perhaps a slight tendency for black openings to be called gambits even when (as here) they're not really so in practice (with world & dog playing 5 b3.).

English: Romanishin Gambit - A13 - 1.c4 e6 2.Nf3 Nf6 3.g3 a6 4.Bg2 b5

Why is this commonly called a gambit?