The thing is that SQL does not use the page file itself. The only way it can affect the page file is if the OS forces SQL's memory out to disk. If it does, there will be error messages in the log stating so. Are there?
If not, then what you may be seeing is a response to the SQL service. It uses memory and, as a result, the OS writes something else into the page file.

Have you checked the perfmon Process counters to see what processes are using the page file?