Technically "a gasket" is a vague term, and COULD be involved.. the WP gasket could be gone, causing it to leak, and allow air in to the system, creating airlock and thus slowing the cooling ability of the system.
Now, since this "problem" isn't stopping you, and isn't "OVERHEATING!!!!", I would actually recommend that you change the WP (at least take the old one out, and you'll be able to see if it was free-spinning, or shattered) BEFORE you go to a mechanic.
Then, if replacing the WP doesn't cover the problem, we can look further in to possible causes of slightly warmer operating temps.
Ray
