This has been answer plenty of time. Next time, please use search feature. Anyway, whatever SHSH hashes that could be saved has to do with what Apple is currently signing, now 4.0.2, and nothing to do with what firmware your phone is on. For some reason, there was time, Apple was signing both 4.0.1 & 4.0.2. Thus, you were able to get both at same time. Probably, why it work for your 3GS. No longer the case and why it's different with your iPhone 4.