Verse 14 is the closest Paul comes to a direct "thank you" to the Philippian congregation - "It was kind of you to share in my trouble." Because of the closeness of his relationship to this church he tells them something he tells no other congregation. Of all the churches Paul planted, and of all the cities he visited, the church at Philippi was the only church to help him out with his ministry on even close to a regular basis. This is telling. Whenever you do anything for Jesus (let alone the great foundation laying work of the apostle Paul!) and almost no one even remembers you're doing it, it takes a fair bit of contentment in Christ and patience for reward in heaven to keep going. I guess we can all learn from that.
The church at Philippi's hearts were so tied to Pauls - and so tied to Christ's - that even when Paul was out of sight and voice they felt their call to be a part of his mission and ministry. Out of sight wasn't out of mind. This is the church shining at its best.