HELP ME GOING BACK ORANGE

Its a little strange for blonde to go back orange...maybe I'm not picturing it right.  Was it dark blonde or light - yellow or white with no darker parts?  (When you said beachy, I pictured light...and that is what it would be unusual if its turning orange again). 

If it was light blonde:  You don't happen to have hard water do you?  With iron in it?  It could be why its mysteriously going orange.  That tends to show up on bleached or light hair and it wouldn't have shown up on dark or resistant gray hair.  If iron in your water is causing it, try a diluted vinegar rinse, or using distilled water as your final rinse after you wash your hair.  (The final rinse with vinegar would be 1tbsp vinegar in 1 cup of water...the smell will evaporate as your hair dries).  This should rinse out any iron stains your hair may be picking up now.

If you don't have irony water, and/or you had gotten darker blonde hair:  That would be a little less strange if its going more orangy, because some of the ashy tone may be washing off.  You said you didn't use any product on it since it was done, does that mean you didn't wash it either? Because especially if you use a harsh shampoo, like a shampoo that says "clarifying" on it....this would also be a stronger acid, so if you think this might be what caused it to go more orange by washing off some of the ashy tone, DON'T try the vinegar rinse above, because that may just make this worse and it wouldn't be necessary anyway.  

So, there could be two things going on then: 
One, if its what I just said, and some of your ash tone is coming off, don't use such a harsh shampoo and consider going back to the salon to have it retoned. 
Two:  If you haven't washed it, so it can't be the shampoo, it could be it was orange yesterday and you just didn't notice because the lighting at a salon is usually very different from your lighting at home.  If this is the case, you may just want to give it a couple of days.  My hair always looks a little orangy for the first few days after I do my roots, but then it fades to yellower blonde.  Its most likely the sun does it.  Mine will also look more orangy on the second day after washing because as the roots get greasier it looks darker and at that state, more orangy. 

I hope that made sense, I feel like I rambled trying to get out everything that crossed my mind.  Hopefully something was helpful!