Something similar to that happened on my '93 SSEi. In my case, it tripped an error code in the ECM, and the problem was the TCC (torque converter clutch) solenoid.
Rather than having the transmission shop rebuild the transmission, I opted for the better 50,000 mile warranty that comes with the rebuilt GM SRTA unit, and I had them install that. There haven't been any problems with the rebuilt transmission.
If yours has a problem at the electrical connector, they should diagnose and fix it, otherwise there'* a problem inside the transmission, and it should be covered by your warranty.
'99 Bonneville SLE, white, 112,000 miles
'02 Park Avenue Ultra, white diamond pearl, 88,000 miles