IDIOMS

small wonder

(idiomatic) An event or fact whose cause or rationale is not difficult to discern; an unsurprising occurrence.

Example: 1891, F. Marion Crawford, The Witch of Prague, ch. 24:
  Small wonder if he had loved her for herself, she was so beautiful.
1908, Jack London, Iron Heel, ch. 1:
  Small wonder that I am restless. I think, and think, and I cannot cease from thinking.
1910, Rabindranath Tagore, The King of the Dark Chamber, Scene 1:
  Small wonder that you can't believe my words—you who think yourself sage enough to reject the opinions of your parents and superiors.
1929, Edgar Rice Burroughs, Monster Men, ch. 2:
  That she was beautiful and intelligent could not be denied, and so it was small wonder that she might appeal strongly to any man.
2004, Jeremy Caplan, "What's Cool In the Pool," Time 16 Aug.:
  Small wonder the average cost of new pools has leaped past $30,000.