Hi jcl007,
Yes … the type of mattress protector you use is one of many things that can have a noticeable effect on sleeping temperature. There is more about the pros and cons of different types of mattress protectors and the tradeoffs involved in each of them in post #89 here and there is also more detailed information about the many variables (including your protector and your sheets and bedding) that can affect sleeping temperature in post #2 here and the other posts it links to.
Phoenix