Transmission question

Sometimes, when I'm doing a dogleg shift down and to the left (i.e., from 4th to 3rd or from 2nd to 1st), the transmission feels like it's going into the gear to the right of the intended target. In other words, I'll be approaching a stoplight in 2nd, blip the throttle and move the gear shift lever to the "1st" position, only the tranny *actually* feels like it's in 3rd! Or, if I were going from 4th to 3rd, it would feel like it was in 5th.

This doesn't happen all the time, and it seems to coincide with (attempted) quick downshifts. If I do it slowly, there's never an issue... Can anyone comment on what this might be related to? If my description doesn't make sense, please let me know, and I'll try to rephrase things better.

Thanks in advance!