Not only that, many states have a waiting period before remarriage is possible. My state, Wisconsin, for instance, specifically states that I can't remarry until six months after the date of the final decree, NO MATTER WHERE I INTEND TO GET MARRIED. When we gave notice at the register office here in Birmingham, aside from checking to make sure I'm really divorced, I'm sure they also checked on this, since it states it right in the papers.
For whatever state and county you believe she filed the papers in (the county of her residence?), do an Internet search for that state's circuit court access. If they have such a thing, you should be able to look by county and his last name to see if there is any kind of divorce action pending...good luck!
(If I was at all interested, I could do this for Wisconsin and keep an eye on whether my ex-husband has gotten into any trouble at all! I see my son got a speeding ticket a while back and paid his fine...)