I would only worry about that value if the phosphorous level was also elevated. My guess is that it was dehydration. It is best to retest at some point after things are well settled.
Qui me amat, amet et canem meum. (Who loves me will love my dog also.), - St. Bernard
"Life without a maltese is like summer without ice-cream." - St. Edelweiss
"Wag more Bark less"