Something's out of wack

[kwhite4]

Had the chance to get some seat time Sat and ran into an issue I couldnt figure out.
During my burn out as I shift into 2nd my wheels stop spinning but it doesnt feel like the motor is free spinning. The passes seemed to go well shifted fine pulled hard , I went my fastest so far 6.69 .
The first 3 trips went normal it didnt do this till the 4th pass .
I wasted the starter and flexplate so I might get trans checked while I have it out but other than that Im stumped.