As long as you used an atf fluid you should be ok.I know lots of people insist on type f and thats ok but there are varying opinions .Some say that type f oxidises quicker and to use a dexron 2 or 3.Others say if you need type f to get a firmer shift then you have a valvebody programming issue.
Personnally i have used dexron 2 + 3 in c4 + c6 for a few years now and never had a prob.
Here's a little side note.Where i work we use allison transmissions.They originally came with dexron 3 which meets the c4 specification. Now after some probs with heating up the oil,allison recommended we fill them with 15/40 engine oil which also meets the c4 spec.Well even with the thicker oil it didn't affect the shifts one bit and actually lasted longer than the dex 3.
Anyway who would have thought to use engine oil.By the way the allisons we use are a 540 series(i think)and are basically a slightly bigger turbo 400.I hope this is useful...