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Concrete with high air content

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I got a question from the field where the Contractor is building a school in a
rural area that is subject to freeze/thaw cycles.  He found that the concrete
had 8% air entrainment where the specifications were for 4%.  ACI 318-95 Table
4.2.1 states that for 1-1/2" aggregate size and for moderate exposure, the air
content should be 4-1/2%.  Is there any effect on the concrete if the air
content is too high?  I couldn't think of any but I though I would throw it
out for discussion.

By the way, it seemed unusual that a Contractor would actually look at such a
small detail (I'm happy when they actually catch the big things) but it turns
out that he was in the process of removing an area of concrete that tests
determined to be low strength so he was looking at the new concrete in detail
and he had already rejected two trucks for low slump.