Is 30mg of meloxicam considered to be an overdose?

That is twice. That is twice the maximum daily dose allowed. 4 cases who took 6-11 times max dose have recovered. But you should avoid doing taking more than 15 mg/day. http://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=a62ec334-f0a3-4e8c-bd17-f85b9135d096.