Calling Someone Elses Client - Is It EVER Acceptable?

Today I was unavailable for a few hours while at my Company picnic in a neighboring city.  At some point, an agent showed one of my listings and decided to write an offer.  The time of the showing was 12:45, the offer was signed at 2:00.  Apparently at some point after that the other agent attempted to call me (I was out of range) but chose not to leave a message.

At 2:15, this agent decides to call MY CLIENT (the seller) to let them know that she had been trying to reach me ALL DAY but I was not answering the phone.

#1)  Are you freakin' kidding me?

#2)  Admittedly, I was out of range... Although, even if I was in range - she didn't leave a message therefore I wouldn't have known to call her back.

Now... I understand when agents are MIA for several hours or DAYS.  However, don't you think that a little common courtesy and professionalism might dictate that you at least leave me a message before calling MY CLIENT to say you can't find me??

If that weren't enough, her offer was SO RIDICULOUSLY low and she had already ticked off my seller that they didn't even want to counter.  *Sigh*

OK, I'm done...  Your thoughts?