I see what they did there.

[shootingstar]

When they reached the shop she saw that something wasn' t right. There were no guitars in the window. There was nothing in the window, except a faded piece of A4 paper stuck on the inside of the glass.
She recognised Neil's handwriting.
Alas, String Theory is no longer able to trade in these premises. Due to an increase in rent we simply couldn't afford to go on. Thanks to all our loyal customers. Don't Think Twice. It's All right. You Can Go Your Own Way. God Only Knows What We'll Be Without You.
Dylan was amused. 'I see what they did there.' Then a moment later. 'I was named after Bob Dylan. Did I ever tell you that?
'I can' remember.'
(The Midnigt Library by Matt Haig, episode Why Want Anothher Universe If This One Has Dogs?)

What does the sentence "I see what they did there" mean in this context. Doesn't it have to be "I saw what they did there?" Why is the simple present "see" used in this sentence? What does the sentence "I see what they did there" actually express there?

 

[jutfrank]

It's a semi-fixed expression, used to say that you understand a joke/reference. In this case, the joke is that the note in the windows makes reference to three very famous songs. I'll guess then that this is a record shop.

I See What You Did There Meaning & Origin | Dictionary.com

I see what you did there is a colloquial expression acknowledging, with appreciation or sarcasm, that one gets a clever joke or witty remark.

www.dictionary.com

 

[shootingstar]

Thank you. String Theory is a music shop. They sell guitars and sheet music.

 

[jutfrank]

String Theory is a music shop. They sell guitars

Ah, I see what they did there.