尽管美元普遍走强，GBPUSD仍保持涨势

I'm leaning towards a technical bounce here. The dollar has been on such a run, it's not surprising to see some pairs take a breather or even gain a little even without specific news.

Could be some positioning ahead of the ECB meeting later this week, or perhaps just a bit of profit-taking on recent USD strength against Sterling.

Interesting point. I've been watching that too. Sometimes these moves can be due to cross-currency flows that aren't immediately obvious from the dollar index alone.