Hard to answer this without more information, however, typically a probation officer will not consider this a violation, in most instances. Temper that against the fact t hat if you have had multiple warnings, lockouts or been a problem probationer in general, they may decide this is enough to file a Motion to Revoke Probation. Best thing to do is hire a lawyer and have them try to negotiate something before an order of arrest goes out and you are greatly inconvenienced.
I agree with Mr. Case's answer. I would add that if this happens again in the future, you should immediately go to one of those testing labs and have a test done (as close in time as possible to the warning or a lock-out) to demonstrate that you have not had alcohol. Those devices have problems frequently, although most judges and probation officers refuse to recognize the problems.