upper/lower case behaviour of results - has it always been this way and I never noticed? Is it a bug?

[chris@shufflepoint]

I think I would have noticed this before. when I use ga:pagepath in a filter, then JSON result has

"columnHeaders": [
    {
        "name": "ga:pagepath",
        "columnType": "DIMENSION",
        "dataType": "STRING"
    },

But if I instead using ga:pagePath in the filter, then results have

"columnHeaders": [
    {
        "name": "ga:pagePath",
        "columnType": "DIMENSION",
        "dataType": "STRING"
    },

Again I am changing the case in the "filters" expression not in the "dimensions" expression.

If I change case in the dimensions expression, I always get back ga:pagePath - which is correct.

Was this a result of a recent change?  I'm thinking this is a bug in the core reporting API.