Yeah, it happened to me. I did a search for various domain names, but didn't settle on anything until the next or two and by then it was taken by a parking page site. This was several years ago, so I don't recall what the domain name was.
Since then I've only searched for names I've been willing to buy right away if it was available.
Happened to me in the .com.au space. Searched a variety of options and made a shortlist. Sat on it overnight and then returned the next day once I'd decided which ones to grab - they (8-10 unrelated domains) were taken.
It's not that much harder - pretty trivial to register under the "close and substantial connection rule" and then have a valid play at it under the service of "domain monetisation."
Years ago it was much more difficult, but since then it's been pretty straightforward. None of these names were trademarks or anything like that so there wasn't anything I could contest.
I use TPP, mostly because they've been pretty easy when it comes to keeping multiple domains under control - easy to delegate to default nameservers, pay by default credit card on file, etc. 95% of the domains I look after (60-70ish personal ones and then others for friends and a bunch more for clients) are .com.au though and I keep the majority of my .coms with TPP also even though they're more expensive - just saves having different logins for every domain with Joker, Gandi, etc.
I guess it makes it a bit easier to charge clients a fraction more (say $50/2yrs) via the same registrar and they don't necessarily feel like you're screwing them.
Likewise, never happened and I've registered close to 300 domains and searched for thousands. I think if this is being done by registrars then they're using people to go through the searches and find ones that meant some sort of "value" quota. I have had domains I wanted registered the next day, but these were things related to "current" things, it was someone else with the same idea as me, that happens sometimes.
3D domain names are hot with domain investors so I would suspect this was not an example of domain name front running, especially if it was a week later.
I kinda have from a company called Easily (March 2008). I used a random domain name and their interface claimed it was already taken for the top TLDs, I don't know if they instantaneously registered it or just lied:
