I was watching Sora no Method 06, and at about 17:03 the line 今日は誘ってくれて嬉しかった came up. Crunchyroll translated the line as "I'm happy you invited me today," but the problem is that she was invited the day before, not today, but Crunchyroll's line made it seem like she was invited today. Is it possible that 今日 only modifies 嬉しかった and doesn't necessarily specify the day that 誘う happened?
4Insert a mental "for" in "invited me for today". It's about the day something is happening, not the day that the invitation was made.– XeoNov 13, 2014 at 22:02
Wouldn't you usually use に when you're using 誘う like that instead of は?– JoeNov 13, 2014 at 23:03
は doesn't behave nicely. It can override に if you topicalize whatever it was attached to, just as it can override を. However, that's not the only way to interpret this sentence. You're absolutely right that it could apply only to 嬉しかった, as "Today, I was happy you invited me."– WlerinNov 14, 2014 at 0:25
Clarification: "can override" in this case means two different things for に and を: を is always replaced outside of poetry or certain other rare contexts, but both は and には are found. Here is some futher discussion: japanese.stackexchange.com/questions/17571/… and the source mentioned in that post: usf.usfca.edu/japanese/Topicalization.pdf– WlerinNov 14, 2014 at 0:41
@Joe: 今日 usually doesn't take に while 日曜日 or １５日 do.– user4092Nov 14, 2014 at 5:44
今日は誘ってくれて嬉しかった sounds perfectly natural to me. I think it's like "Thank you for asking me out for today." implying "Today, I had a great time."
今日誘ってくれて嬉しかった sounds to me like "I was happy you asked me out TODAY, not another day."
That 今日 indicates the day when she felt happy. If it's the day when she was invited (for), the sentence would be 今日誘ってくれて嬉しかった.