Likewise, I have not had any issues until a couple of weeks ago but am now getting quite an amount of Spam email.
When I look at my form, what I see where the reCaptcha image should be is:
[recaptcha]
Exactly like it appears in the contact form.
The site and secret keys are still valid according to Google and if I run the ‘Test reCAPTCHA’ it tests and verifies perfectly.
Any suggestions appreciated.