Gary, those seals are RIGHT THERE when you start to tear into it. No reason not to do it, probably $10 for all the seals. Rosenthal Mazda has a "timing belt kit" that includes everything, belt, pump and seals. All real Mazda parts. I did mine last year at about 78K and the belt that came out looked brand new. Even though Mazda says to do it at 60K, California Miatas are scheduled to do it at 90 or 100K (per orders of the STATE.
There is a very large safety factor involved in Miata belts. If you do decide to do it you can find Rosenthal on the Miata forum, he is a sponsor. When I changed mine it took me 11 hours but I worked very slowly and did everything 2 or 3 times to "make sure". Somewhere on this forum in my in mailbox there is a very detailed "how to do" write up including pictures. Not sure I can transfer it but if you want I'll try to get it. Bob