I have experienced this same problem from time to time.  At least in one
case, it was not long after restarting that I herd the water pump bearing.
Up to this point, I had not had the hot starting problem for a long time and
then this occurred.  In checking the van (after pulling over to the side and
stopping the engine), sure enough it was the water pump hanging up.
Anything connected via belts to the main shaft will cause a strain on the
starter if it is trying to turn a bearing that is seizing up to any extent.
 I found a similar problem affecting our Lincoln with respect to mileage.
The small 6 cylinder pushing around that heavy body notices a big drop in
mileage when one of the pumps starts having problems.  Sometimes you can
even feel it in the engine when you are driving but it is not yet bad enough
to make a noise.

William