why would the automatic transmission get stuck in first gear occasionally? on 2005 Mercedes-Benz SL500

This has occurred several times but seems to shift properly if I shut the car off and restart it.

Get Your Car Fixed at a RepairPal Certified Shop.
We certify shops based on expertise, quality work, and verified customer reviews
2 answers
possibly low fluid level...
SEEK A FREE DIAG AND EST FROM AAMCO THEN SHOP PRICES