The Mail Adventures of the Smelling Roses

On 14 May, Correos issued this stamp dedicated to the 70th anniversary of a Rose Garden in the Parque del Oeste (='West Park') in Madrid.

I bought a 7-stamps set like this one, the surprise was that it smelled like roses! So, I used the sheet to add some sweet scent to letters to Portugal, the UK and the USA:

And now, for the odd mail adventures: two of them were posted on 14 July, but got postmarks on 22 July. The third one was posted on 16 July in the same mailbox and postmarked the following day, 17 July. How do you explain that?

And still an extra mail adventure for the one I sent to the UK: it arrived open (meh!) but luckily nothing was lost in way. And it got two postmarks, from Correos (22 July) and Royal Mail (25 July).