Hi Richard,
Yes there is. On some chips (not the 16F648 though, I believe) the timer is dubble buffered so you don't need to worry about it. On chips where it isn't you do need to cater for it by reading TMR1H "on both sides" of reading TMR1L and comparing the result to verify that it didn't roll over.

As I said, the example is a bare bones approach. I didn't want to put too much into it before getting more details.

/Henrik.