Crock pot turned to warm for 45mins- 1hr
The USUAL problem with "warm" (or off/unplugged) on a crockpot is when food that is not hot is placed in one and left on those settings, where it does not quickly warm to a safe temperature range.

If the food was on "High" for 2 hours, it was hot. Depending on the specifics of the "warm" setting on your crockpot, it's somewhere between no risk (warm is 140F or above, maintaining a safe serving temperature) or low risk if for some bizzare reason they set it lower (food would still take a long time to cool below 140 °F, and thus would not actually have been below that temperature for anywhere near the full 45 minutes.) 

I honestly can't imagine that a manufacturer would have chosen the second (unsafe) option, but I don't know for sure what your specific model actually does.